A dairy farm milking system is for harvesting milk from animals such as cows and goats. Such a system is typically installed within a barn or other building, and is configured to extract, convey and temporarily store the milk being harvested from the animals.
Various dairy farm milking systems are known. For example, a milking parlour typically refers to a system in which each animal enters a milking station for extraction of their milk, whereas a milking stall system is one in which each animal is positioned in a respective stall and the producer (i.e., a farmer) goes from stall to stall to extract the milk Some dairy farm milking systems are primarily automated, using robotics, lasers and/or image-capture devices to align extraction equipment such as a milking unit to the particular animal being milked Other dairy farm milking systems are configured such that manual application of the milking unit to the animal is required.
A common dairy farm milking system includes at least one milking unit, a fluid line having an air section and a liquid section, a receiver jar, a vacuum subsystem, and a milk bulk tank.
Each milking unit is generally configured to couple with, and extract milk from, the udder of the animal. The milking unit is arranged to be in fluid communication with both the air section and the liquid section of the fluid line, and employs vacuum imparted to the fluid line by the vacuum subsystem to coax milk out of the teats of the animal for conveying into and through the liquid section of the fluid line. During the coaxing, continuous vacuum is applied via the air section of the fluid line to the teat cups of the milking unit that respectively receive the teats to ultimately create a pressure difference across each teat canal thereby to coax the milk from the teat. In order to relieve the animal's teat from constant pressure, atmospheric air is periodically admitted into the milking unit at a pulsation rate of about once per second.
The milk extracted from the animal is conveyed under vacuum through the liquid section of the fluid line to a receiver jar, and is in turn conveyed to the milk bulk tank for cooling and storage. The air section of the fluid line is also in fluid communication with the receiver jar. It is at the receiver jar that the air and liquid sections of the fluid line meet. However, due to the respective locations at which each of the air and liquid sections enter the receiver jar, liquid in the liquid section generally cannot enter into the air section.
While there are various cycles that could be employed for milking and cleaning fluid lines, it is generally the case that, prior to and after milking, chemical and water rinses with chlorine or other treatment materials are conducted to cleanse the fluid line of bacteria and any other unwanted elements so that they are not carried by the milk into the milk bulk tank.
In the case of an animal such as a cow or goat, the udder extends below the animal close to the hind legs and the floor on which the animal is standing. During milking, the milking unit must therefore be positioned accordingly. However, the floor on which the animal is standing is typically at least somewhat soiled with the animal's fecal matter and urine which can, along with the surrounding air, contain high levels of bacteria. Furthermore, during milking the animal is generally free to expel fecal matter and urine, and animals can jostle the milking unit with their legs. As such, the inventors have considered that the milking unit admitting atmospheric air into the teat cup at the pulsation rate can, in doing so, also admit significant amounts of air borne bacteria into the stream of milk being extracted.
Furthermore, the inventors have also considered that air borne bacteria may also be admitted into the stream of milk via the vacuum subsystem. In particular, the vacuum subsystem may include one or more vacuum pumps that are coupled to the fluid line for imparting the vacuum to the fluid line when actuated, and one or more vacuum regulators for permitting atmospheric air to enter into the fluid line to regulate vacuum pressure levels within the fluid line. In the event that a particular vacuum regulator is positioned near to areas having high levels of air borne bacteria within the building or even outside of it, that bacteria will be swept up along with the atmospheric air via the vacuum regulator into the air section of the fluid line and ultimately into the milk.
High levels of bacteria within milk present health risks to those who will consume the milk and the milk products derived from the milk such as cream and cheese. While downstream processes such as pasteurization at the milk processing plant are for reducing levels of unwanted bacteria, many milk marketing regulators will penalize a producer in the event that bacteria levels in a sample of tested milk exceeds an acceptable level. For example, the Milk and Milk Products Regulation (R.R.O. 1990, Regulation 761) enabled by the Milk Act in Ontario, Canada (R.S.O. 1990, CHAPTER M.12) specifies that milk being produced by a producer shall be tested for bacteria levels at least once per month. In order for tested milk to be considered grade 1, it must have less than 50,000 bacteria per milliliter of milk. In the event that tested milk has 50,000 or more bacteria per milliliter of milk, it is considered grade 2. If a series of milk tests results in the milk from a particular producer remaining at grade 2 over a threshold number of monthly tests, the producer will be held liable for a financial penalty the amount of which is based on the volume of milk. The producer's milk may ultimately be refused for marketing if the high bacteria levels persist over time. Meanwhile, the animals will continue to require milking in order to stay healthy, and the costs of disposing unmarketable milk will fall on the shoulders of the producer.
Due to the potentially significant financial penalties and disruptions accruing to a milk producer as a result of high bacteria levels in the milk, it is important for the producer to maintain bacteria levels to within an acceptable level.